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Irrigation Well

Irrigation well

Primary Purpose

The Basic Data Unit is the Arizona Department of Water Resources primary source of groundwater data.  Basic Data (BD) is responsible for collecting groundwater levels and some water quality data throughout Arizona as well as developing Hydrologic Map Series (HMS) reports and Water Level Change Map Series (WLCMS) reports.  HMS reports are in-depth studies of groundwater conditions by basin and WLCMS reports provide water level data from the two most recent collection periods within a basin. BD along with Geophysics/Surveying are also responsible for conducting a wide variety of data collection activities in support of the Statewide Hydrologic Monitoring Program.


Manual Data Collection

Basic Data uses several methods for data collection.  For many years now its primary groundwater level measurement method has been an electronic sounder or a steel tape that take a discrete measurement.  BD uses these methods to measure a series of approximately 1,800 “Index wells” annually across the state. In addition BD periodically conducts basin sweeps to measure water levels for all accessible wells within a specific basin or sub-basin. View the Basic Data Fact Sheet pdf (2.1 MB) for more information.

View members of our BD Team taking a deep water-level measurement at the City of Williams' Rodeo Grounds Well # 55-584106 pdf (3.5 MB).

Statewide Automated Groundwater Monitoring

In approximately 113 wells throughout the state, BD uses automated groundwater monitoring devices that record water levels on a predefined frequency on a continuous basis.  BD deploys automated data collection systems in the form of pressure transducers and shaft encoders that measure water levels 4 times daily and store the data electronically. BD retrieves the data quarterly by downloading the data to a lap top or flash memory card or the well may be equipped with satellite telemetry systems for near real-time measurements.  For more information please view the Statewide Automated Groundwater Monitoring Fact Sheet pdf (1MB).

Groundwater Site Inventory Database

BD stores its groundwater data in an ORACLE database titled Groundwater Site Inventory (GWSI).  GWSI is a field verified database consisting of thousands of wells; including locations, current and historic water level information and numerous associated data relating to those wells. 



Peoples Valley

Automated Transducer Well Site

Where to Get Data                                                             

Groundwater data can be viewed online using the GWSI Database and Wells Registry Database Interactive Maps.

HMS reports and WLCMS reports are available online at the Hydrology eLibrary or may be purchased in print.   

If you wish to purchase copies of the HMS reports or WLCMS reports please contact Information Services at 602-771-8627 for more information.


Hydrology Division Navigation Links

Use the above links to navigate the Hydrology Division